Development and control of a low-cost linear variable-reluctance motor for precision manufacturing automation

Most advanced manufacturing processes require precise linear-position control for material transfer, packaging, assembly, and electrical wiring. To achieve precise linear motion, most of these high-performance manufacturing machines use X-Y sliding tables with permanent-magnet rotary motors and rotary-to-linear couplers. Though this method is the most widely used, it has disadvantages of low accuracy, complex mechanical adjustments, high cost, and low reliability. This paper describes the use of the variable-reluctance-driving principle to construct a novel linear direct-drive actuator system for high-performance position control in manufacturing automation. The proposed actuator has a very simple structure and it can be manufactured easily. There is no need for magnets and no limitation on the traveling distance. The actuator is extremely robust and can be used in hostile environment. A novel control method, using cascade control and the force-linearization technique, is developed and implemented for precision position control of the actuator. Experimental results of the motion system indicate that the system has fast responses with good accuracy.